1. Field of the Invention
The present invention relates to a conveyance apparatus for coating in which a workpiece which is supported on a conveyor can be coated while its position being changed, and more particularly to a conveyance apparatus which is suitable for high quality spray coating.
2. Description of the Prior Art
In a coating line for a vehicle, there are many treating processes such as pretreatment, electrodeposition, washing, coating, and drying. A workpiece is transferred among these treating processes by a conveyor. The workpiece is usually supported on a floor conveyor that is provided on a floor or supported in a condition where it is hung from an overhead conveyor that is provided overhead. Also, in the case of electrodeposition coating, to obtain a fine coating quality, it is known that the workpiece must be rotated in an electrodeposition paint tank so that its position is changed to a successive variety of positions (e.g. see Japanese Patent Publication No. Hei 6-104920 and Japanese Unexamined Patent Publication No. Hei 2-111481).
In the case of spray coating, since the workpiece is coated while being conveyed by the overhead conveyor in a spray booth, a spray apparatus side must be positioned corresponding to a fixed workpiece position during painting. In this case, a region remains in which coating is difficult, and modified or additional coating work is required. There is also a part where coating is inefficient, relating to conveyance by the overhead conveyor. Unlike a dipping treatment such as electrodeposition coating where simple rotation of the workpiece is required, it is difficult to perform satisfactory coating of the region where spray painting is difficult.
It is therefore an object of the present invention to solve the above-mentioned disadvantages.
To solve the above-noted disadvantages, according to the present invention, a conveyance apparatus is provided for spray-coating a workpiece which is supported on a conveyor by means of a carrier while passing through a spray booth, the conveyance apparatus for coating being characterized in that a position control mechanism which is capable of changing the position of the workpiece to more than one of a floor conveyor position, an overhead conveyor position, or a side conveyor position is provided, and the workpiece position is controlled by the position control mechanism so that all surfaces to be coated are turned to face a nozzle of a spray apparatus.
The position control mechanism can be constructed to be capable of vertical and horizontal rotation. It can also be constructed so that all the surfaces to be coated are coated in a level plane.
According to the present invention, a position control mechanism is provided that can change the position of a workpiece to more than one of a floor conveyor position, an overhead conveyor position, or a side conveyor position. By continuously changing the position of the workpiece to more than one of these positions in combination, the workpiece position can be controlled so that all surfaces to be coated face in the direction of a nozzle of a spray apparatus. As a result, even though the workpiece passes through a spray booth while being supported on the same conveyor, the workpiece is controlled to occupy the most suitable workpiece position so that all surfaces to be coated are spray-coated in a satisfactory condition. It is therefore possible to improve the efficiency of the spray painting.
Also, if the position control mechanism enables the vertical and horizontal rotation, it is possible to perform more complicated position control in which the position of the workpiece is changed to more than one of the floor conveyor position, the overhead conveyor position, or the side conveyor position. Thus, more accurate coating can be performed. By keeping the workpiece in the side conveyor position, each surface can be coated in a level plane. It is therefore possible to form a satisfactory coating film by spray painting from a nozzle situated above the workpiece.